Breeding phenology and postnatal development data of northern bats (Eptesicus nilssonii)
Abstract
Bats inhabiting northern latitudes are faced with short reproductive seasons during which they must produce and rear pups before fattening up in time to survive the winter hibernation. Therefore, the timing of parturition has considerable impacts on future fitness prospects for mother and pup. However, little is known about individual variation in breeding phenology and its consequences for postnatal development within bat populations. Here, we studied the phenology of breeding in Eptesicus nilssonii across seven years using data collected by day-to-day monitoring of a breeding colony in Norway (60.1°N) for which the identity and age of each mother (N = 8) and pup (N = 28) were known. Using mixed-effect models, we found that arrival at the colony was influenced by temperature conditions from mid-April to mid-May across all females, but that there were strong and consistent individual differences in arrival- and parturition time across years. Females generally arrived ~32.1 days before giving birth but the gestation duration was reduced if females arrived late, and prolonged if females left the colony when faced with cold weather conditions. Pups born later in the season were born smaller but had higher growth rates during the most rapid growth period (<10 days old). The within-individual effects suggest that the higher growth rates could be due to mothers compensating (e.g. through increased food intake) for late parturition rather than by improved food availability. Date of parturition did not influence adult body size in pups. Pups became volant at the earliest only 13.1 days after birth and approached adult flight patterns during their first flight week. Our results suggest that E. nilssonii is highly adapted to a short breeding season by producing large, fast developing and early volant pups, despite the environmental pressures bats face at northern latitudes.
README: Breeding phenology and postnatal development data of northern bats (Eptesicus nilssonii)
https://doi.org/10.5061/dryad.8sf7m0czk
Description of the data and file structure
Data on breeding phenology and postnatal development in Eptesicuss nilssonii, collected in a small maternity colony in Nittedal (Norway) between 2017-2023. Missing values in the dataset are indicated with NA. The excel-file contains 8 spread-sheets, described in more detail below:
Spreadsheet Baby growth
A dataset which contains details on the development (forearm-length and body mass) of each pup born during the study period. The variables are the following:
Year: the year the observation was made
TimeDate: the date and time of the observation
BabyBorn: the date the observed pup was born
Baby: ID of the pup
Sex: sex of the pup
HoursOld: age of pup at observation, reported in hours (negative values indicate time before pup was born)
DaysOld: age of pup at observation, reported in days (negative values indicate time before pup was born)
Forearm: forearm length of pup, measured in mm
Weight: body mass of pup, measured in grams
Mother: ID of the mother
MotherWeight: body mass of mother, measured in grams
MotherFA: forearm length of mother, measured in mm
MotherBorn: year of birth of the mother
MotherAge: age of the mother
Spreadsheet Phenology
Data on phenology and yearly observations. The variables are the following:
Year: the year the observation was made
Spring_Onset: ordinal day of spring, calculated as the ordinal day where the 10-day smoothed daily temperature is above 0C for at least 10 days
Mother: ID of the mother
Mother age: Age of the mother
Mother_arriving: Date the mother arrived in the bat box in spring
Days from arrival to birth: Number of days from arriving in the box until giving birth
Days missing early: Number of days mother is missing from the box in early pregnancy (less than 16 days after arriving in the box in spring)
Days missing late: Number of days mother is missing from the box in late pregnancy (more than 15 days after arriving in the box in spring)
Baby: ID of pup
Sex: Sex of pup
Born: Date and time pup was born
BP lm growth: linear growth rate of forearm length of pup during the most rapid growth period (before 10.6 days old)
Adultsize_FA: Largest recorded forearm length in pup
Mom_FA: Forearm length of mother
BP BM lm growth: linear growth rate of body mass of pup during the most rapid growth period (before 9.6 days old)
Max BM 20days: Highest recorded body mass of pup before it was 20 days old
Umb cord last obs: Time of last observation of umbilical cord being attached
Umb cord age: Age of pup when umbilical cord was last observed being attached
OpenEyes: Time of eyes being open for the first time
Age_OpenEyes: Age of pup when opening eyes
First_flight: Time for pup's first flight
Age first flight: Age of pup at first flight
Mother leaving first time: Date of mother leaving the colony for the first time in the late summer
Baby leaving: Date of pup leaving the colony for the first time in the late summer
Age leaving: Age of pup when leaving the colony for the first time
Spreadsheet GLM data arrival
Data for binomial model to predict probabilities of mother leaving the bat box during the gestation period. The variables are the following:
Year: the year the observation was made
Mother: ID of the mother
StartDate: Date of observation
Present: Value indicating if mother is present (1) or not present (0) in the box
Birth: Date and time for the birth of the pup
Time_left: Days left until birth
Days after arrival: Number of days since mother arrived in the box in spring
Spreadsheet Weather three weeks to birth
Meteorological data during the three weeks before a pup was born. The variables are the following:
Baby: ID of pup
Born: Birth date and time of pup
DateTime: Date and time for meteorological observation
Year: Year of observation
Min temp: Minimum temperature measured past hour
Max temp: Maximum temperature measured past hour
Measured temp: Temperature measured
Rain mm: Total rainfall (in mm) the past hour
Wind ms: Mean wind speed (ms) the past hour
MaxWind ms: Max wind speed (ms) the past hour
Station ID: ID of meteorological station
StationName: Name of meteorological station
Sunrise next day: Date and time of the following sunrise
Sunset: Date and time of the sunset
Day night: Whether the observation was made during the day (before sunset) or during the night (after sunset)
Spreadsheet Environmental data (hourly)
Hourly meteorological data each summer of observing. The variables are the following:
DateTime: Date and time for meteorological observation
Year: Year of observation
Min temp: Minimum temperature measured past hour
Max temp: Maximum temperature measured past hour
Measured temp: Temperature measured
Rain mm: Total rainfall (in mm) the past hour
Wind ms: Mean wind speed (ms) the past hour
MaxWind ms: Max wind speed (ms) the past hour
Station ID: ID of meteorological station
StationName: Name of meteorological station
Sunrise next day: Date and time of the following sunrise
Sunset: Date and time of the sunset
Month: Month the observation was made
Day night: Whether the observation was made during the day (before sunset) or during the night (after sunset)
Spreadsheet Env data 3 weeks babygrowth
Meteorological data during the three weeks after a pup was born. The variables are the following:
Baby: ID of pup
Born: Birth date and time of pup
DateTime: Date and time for meteorological observation
Year: Year of observation
Min temp: Minimum temperature measured past hour
Max temp: Maximum temperature measured past hour
Measured temp: Temperature measured
Rain mm: Total rainfall (in mm) the past hour
Wind ms: Mean wind speed (ms) the past hour
MaxWind ms: Max wind speed (ms) the past hour
Humidity: relative humidity in the air (%)
Station ID: ID of meteorological station
StationName: Name of meteorological station
Sunrise next day: Date and time of the following sunrise
Sunset: Date and time of the sunset
Month: Month the observation was made
Day night: Whether the observation was made during the day (before sunset) or during the night (after sunset)
Spreadsheet Emergence juveniles
Observations of emergence time of juveniles. The variables are the following:
Year: Year of observation
StartDate: Date (before midnight) of the observation
DateTime leave: Date and time for emerging from the box at night
StartDate figure: Date (before midnight) of the observation, with the year changed to a common year for visualisation purposes
DateTime figure: Date and time for emerging from the box at night, with the year changed to a common year for visualisation purposes
Age: Whether observation is for a pup (juvenile) or mother (adult)
FN_Karl: Flight night (1 is the first night pup flew out, 2 is the second, etc) of the pup with the ID Karl
FN_PerOle: Flight night of the pup with the ID PerOle
FN_MJ: Flight night of the pup with the ID Marie-Jo
FN_Paul: Flight night of the pup with the ID Paul
FN_Rune: Flight night of the pup with the ID Rune
FN_Moritz: Flight night of the pup with the ID Moritz
FN_Age: Flight night of the pup with the ID Age
FN_Tony: Flight night of the pup with the ID Tony
FN_PerInge: Flight night of the pup with the ID PerInge
Spreadsheet Trip duration juveniles
Observations of trip durations during foraging flights of juveniles. The variables are the following:
Year: Year of observation
StartDate: Date (before midnight) of the observation
DateTime leave: Date and time for leaving the box at night
DateTime return: Date and time for returning after leaving
flight duration min: Duration from leaving until returning (in minutes)
pause time: time from returning until flying out again
Number trips: number of trips registered for an individual
Trip type: Type of trips, either "main" (first trip of the night) or "extra" (any trips made after the main trip)
Age: Whether observation is for a pup (juvenile) or mother (adult)
Flight night: Flight night of pup (1 is the first night pup flew out, 2 is the second, etc)
Code/software
Excel can be used to view the data file